1. Technical Field
The present invention broadly relates to methods and devices for treating fluent materials for purposes of mixing, reacting, conditioning and the like, and deals more particularly with a method and apparatus of this general type which imparts pulses of energy to the fluent materials by subjecting the flow of fluent materials to rapid, periodic changes in pressure.
2. Description of Prior Art
The fluid treatment art is replete with improved mechanical, pneumatic, hydraulic and electrical systems for mixing, agitating, reacting and conditioning fluent materials. In some of these systems, such as those dedicated to mixing operations, operating efficiency and effectiveness are dependent upon the degree of mass transfer of the fluent materials being mixed. Mass transfer is a function of the probabilities that particles/molecules of the differing fluent materials being mixed are exposed to each other, and this exposure depends in part upon the surface area presented by the particles/molecules of the different materials. In order to increase the probabilities for complete dispersal of the materials, mixing time may be increased. This alternative is available in the case of "batch" processing but may not be feasible in continuous type mixing processes where the resident time of the fluent materials in a mixing vessel is necessarily limited. Moreover, extending the duration of mixing or applying excessive amounts of energy in the mixing process may result in fracturization or excess micro-pulverization, producing undesirable fine dust or even degradation of the component parts of the materials being processed.
Various improvements have been devised to facilitate more efficient mixing and increase dispersion rates. For example, a device typifying one solution to this problem is disclosed in U.S. Pat. No. 4,874,248 issued Oct. 17, 1989 to Luetzelschwab. The Luetzelschwab device comprises a plurality of alternately arranged, stationary and rotating disks within a cylindrical housing which is intended to be employed for continuously mixing a gel and a liquid. The disks contain apertures through which the gel and liquid flow in order to break down the gel into smaller particles and increase the gel surface exposed to the liquid. A similar mixing device is shown in French Patent No. 1,287,425 which employs alternating fixed and rotating perforated plates to shear, chop and divide solid particles suspended in a liquid, or to mix different liquids. Further examples of mixers of this general variety are shown in German Patent Nos. 901,011 and 1,026,107. Prior art mixers of the type described immediately above, while adequate for certain applications, provide less than satisfactory efficiency in other applications. In some cases, the requisite degree of mixing may be achieved only with long resident times in the mixer, thus dictating, in the case of continuous type processes, a mixer of large physical dimensions in order to provide a long flow path within the mixer. Physically large mixers normally add to expense and typically consume larger amounts of energy to operate. In fact, in some of rotating/stationary disk type mixers, the disks are actually configured to create turbulence and increase the flow path (and thus residence time) so that they act more like batch processors.
Numerous types of processes are known for treating fluent materials to alter/improve their physical characteristics which involve the direct application of pulses or waves of energy to the materials. For example, U.S. Pat. No. 4,957,606 issued Sept. 18, 1990 to Juvan discloses a process for separating substances from liquids using high energy discharge initiated shock waves. U.S. Pat. No. 4,961,860 issued Oct. 9, 1990 to Masri discloses a water treatment process in which the water is subjected to ultrasonic vibrations producing cavitation of water through a fluid flow passage. The use of acoustical energy in standing waves for manipulating and separating fluent particles is also disclosed in U.S. Pat. Nos. RE33,524; 4,877,516 and 4,983,189.